nvmem: Add the Broadcom OTP controller driver

Add support for 32 and 64-bit versions of Broadcom's On-Chip OTP
controller. These controllers are used on SoC's such as Cygnus and
Stingray.

Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Tested-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Oza Pawandeep <oza@broadcom.com>
Signed-off-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>